[Altay-]

Having recently finished The Rise and Fall of American Growth myself, I reached the opposite conclusion.

Yes, the decrease from 12+ -> 8 hour workdays helped health and thus productivity and growth as the author persuasively states. But in the final few chapters which look forward rather than back in time, it was my interpretation that the author sees trends in declining hours & labor force participation as headwinds to TFP growth.

It is naturally more inefficient to have more shifts and thus more people commuting, etc. The diminishing health returns from 8 - > 6 hour work days not being enough to make up for this loss in efficiency.